北京地区雷暴过程闪电与地面降水的相关关系

Relationship Between Lightning Activities and Surface Precipitation in Thunderstorm Weather in Beijing

该文选取北京地区2006年夏季的18次雷暴过程,利用SAFIR3000三维闪电定位系统观测到的总闪数据,分析了闪电与雷达反演的对流活动区降水量和对流活动区面积的相关关系,结果表明：北京地区的雷暴活动中,单个闪电所表征的降水量的范围在0.86×10^7～6.57×10^7kg/fl之间,平均值为2.65×10^7kg/fl;闪电活动与对流活动区降水量的线性相关关系显著,相关系数达到0.826;闪电活动与对流活动区面积也具有显著的线性关系,相关性系数达到0.846。文中给出了基于6 min闪电频次估算6 min对流降水量以及对流活动区面积的拟合方程。分析还发现,总闪活动与降水的关系要明显好于地闪,总闪信息的应用极大提高了分析结果的质量和可信性,分析结果对于利用闪电信息估测降水具有参考意义。

Study on the relationship between lightning activity and precipitation is valuable for estimating the rainfall based on lightning detection in the areas where other observation methods such as radar,precipitation gauge and so on are inapplicable.Therefore,18 thunderstorm processes occurred in Beijing area are investigated based on radar observation and correlative radar algorithms,then the convective regions and stratiform regions are distinguished and the precipitation intensity of the thunderstorms is calculated.The total lightning data（intracloud（IC） lightning and cloud-to-ground（CG） lightning） of the thunderstorms detected by SAFIR3000 3-D total lightning location system is used in the analysis to discuss the relationship between the lightning activities and the amounts of precipitation in convective regions and the areas of convective regions.It is found that the precipitation per flash（PRF） ranges from 0.86×10^7 kg/fl to 6.57×10^7 kg/fl with the average value of 2.65×10^7 kg/fl.Through comparing the standard deviation of the PRF calculated based on total lightning（PRFL） and that calculated based on CG lightning（PRFCG）,it shows that PRFL is more stable than PRFCG in different thunderstorms.It demonstrates that for the time series of the peaks of lightning activities and the peaks of the amounts of precipitation in convective regions and the areas of convective regions,there are three styles of situation,i.e.,ahead,behindhand and synchronous, which shows the complex relationship between them.The significant linear correlations between lightning activities and the amounts of precipitation in convective regions are found in all thunderstorms. The statistics including all samples shows that the coefficient is 0.826 and the fitting equation is MCR=1.574×10^7FTL＋2.956×10^8.FTL is the frequency of the total lightning in 6 min and MCR is the amount of precipitation in convective regions in 6 min with the unit of kg/6 min.According to the situation of the time series of the peaks of lightning activities and precipitation,every thunderstorm process is divided into three stages：Rising stage,intermediate stage and falling stage.The correlation between lightning activity and the precipitation is found to be the most significant during the rising stage,followed in turn by falling stage and intermediate stage,and the corresponding coefficients are 0.859,0.853 and 0.736,respectively. The relationships between the lightning activities and the areas of convective regions are found to be outstanding in 16 thunderstorms.When all the thunderstorms are considered,the coefficient reaches 0.846 and the fitting equation is ACR=4.267FTL＋130.283.ACR is the area of convective region with the unit of km^2 and FTL is the frequency of the total lightning in 6 min.According to the time series of the peaks of the lightning frequencies and the areas of convective regions,the thunderstorm processes are divided into three stages in the same way.It shows that all the linear correlations for three stages are outstanding, especially for rising stage.The coefficients for rising stage,intermediate stage and falling stage are 0.862, 0.834 and 0.837,respectively.Through the analysis,it is found that the relationships between the total lightning activity and the precipitation in convective region and the area of convective region are always better than those between the CG lightning activity and the precipitation and the area,indicating that the application of the total lightning data has improved the quality and reliability of the results.